High; Hot; Humid. Those are the three things that de-power aircraft to the point where they cannot gain altitude.

They may go back and re-figure their apparent altitude and find there is no way that particular aircraft could make an altitude gain or a turn (that's when it failed) on that day from that airport carrying that load.

They would not be the first to fail to do the math before takeoff. The Wichita State football team was killed that way:

Quote:

"The intentional operation of the aircraft over a mountain valley route at an altitude from which the aircraft could neither climb over the obstructing terrain ahead, nor execute a successful course reversal. Significant factors were the overloaded condition of the aircraft, the virtual absence of flight planning for the chosen route of flight from Denver to Logan, a lack of understanding on the part of the crew of the performance capabilities and limitations of the aircraft,.........